1. Field of the Invention
The present invention relates to a light guide plate employed in a backlight module, and particularly to a light guide plate having V-shaped grooves configured for high and uniform brightness.
2. Description of Related Art
Because a liquid crystal display (LCD) device has the merits of being thin, light in weight, and drivable by a low voltage, it is extensively employed in various electronic devices.
A liquid crystal panel of an LCD device cannot itself emit light beams. Therefore a typical liquid crystal panel uses a backlight module to provide the needed illumination. The backlight module has a light source and a light guide plate. The light source emits the light beams to the light guide plate, which then transmits the light beams to illuminate liquid crystal panel.
Referring to FIG. 14, one kind of typical backlight module is shown. The backlight module 1 comprises a light guide plate 2 and a light source 3. The light guide plate 2 has a bottom surface 5 and an emitting surface 4. The light source 3 is set adjacent one corner of the light guide plate 2. A plurality of parallel, V-shaped grooves 6 is defined at the bottom surface 5. The V-shaped grooves 6 are arc-shaped. For each V-shaped groove 6, every point along an apex of the V-shaped groove 6 is substantially equidistant from the light source 3. The V-shaped grooves 6 all have a same width and a same height. More particularly, a density of the V-shaped grooves 6 is uniform in a direction away from the light source 3.
When light beams from the light source 3 strike surfaces of the light guide plate 2 at the V-shaped grooves 6, the incident angles of the light beams differ according to the heights at which the light beams reach the V-shaped grooves 6. In other words, some incident angles are relatively large and some incident angles are relatively small.
When the incident angles are large, the light beams typically are reflected from the surface at the V-shaped groove 6, whereupon the light beams emit from the emitting surface 4. Such light beams are not refracted at the surface.
In contrast, when the incident angles are small, the light beams typically are reflected and also refracted from the surface at the V-groove 6. The refracted light beams are wasted. Thus the overall utilization of light beams by the light guide plate is lowered, and illumination provided by the emitting surface 4 is liable to be non-uniform.
It is desired to provide a new light guide plate and a corresponding backlight module which overcome the above-described problems.